Endocrine, Cardiovascular, and Blood Vessel Systems: Study Guide for Anatomy & Physiology

Chapter 18: Endocrine System

Overview of the Endocrine System

The endocrine system is a network of glands that secrete hormones directly into the bloodstream to regulate various body functions. It works closely with the nervous system to maintain homeostasis.

• Endocrine glands: Ductless glands that release hormones into the blood.

• Hormones: Chemical messengers that regulate physiological processes.

• Major processes controlled: Metabolism, growth, reproduction, stress response, and homeostasis.

Major Endocrine Glands and Their Functions

• Hypothalamus: Links the nervous and endocrine systems; produces releasing and inhibiting hormones that control the pituitary gland.

• Pituitary gland: The "master gland"; anterior and posterior lobes secrete hormones that regulate other endocrine glands and various body functions.

• Pineal gland: Secretes melatonin, which regulates circadian rhythms.

• Thyroid gland: Produces thyroid hormones (T3 and T4) that regulate metabolism, growth, and development.

• Parathyroid glands: Secrete parathyroid hormone (PTH), which regulates calcium levels in the blood.

• Adrenal glands: Produce hormones such as cortisol, aldosterone, epinephrine, and norepinephrine; involved in stress response and metabolism.

• Pancreas: Has both endocrine and exocrine functions; endocrine portion secretes insulin and glucagon to regulate blood glucose.

• Gonads (ovaries and testes): Produce sex hormones (estrogen, progesterone, testosterone) involved in reproduction.

Key Hormones and Their Functions

• Anterior Pituitary Hormones: ACTH, FSH, LH, GH, PRL, TSH

• Posterior Pituitary Hormones: Oxytocin, ADH

• Thyroid Hormones: T3 (triiodothyronine), T4 (thyroxine), calcitonin

• Parathyroid Hormone: PTH

• Adrenal Cortex Hormones: Cortisol, aldosterone, androgens

• Adrenal Medulla Hormones: Epinephrine, norepinephrine

• Pancreatic Hormones: Insulin, glucagon

• Pineal Hormone: Melatonin

Hormone Regulation and Feedback Mechanisms

• Hormone secretion is often regulated by negative feedback mechanisms to maintain homeostasis.

• Example: Rising blood glucose stimulates insulin release; insulin lowers glucose, reducing the stimulus for further insulin secretion.

Disorders of the Endocrine System

• Gigantism, Acromegaly: Excess growth hormone

• Goiter: Thyroid gland enlargement, often due to iodine deficiency

• Graves Disease: Autoimmune hyperthyroidism

• Cushing's Syndrome: Excess cortisol

• Addison's Disease: Adrenal insufficiency

• Pheochromocytoma: Tumor of adrenal medulla

Chapter 19: Cardiovascular System – Blood

Blood Composition and Functions

Blood is a connective tissue composed of plasma and formed elements. It transports substances, regulates body functions, and protects against disease.

• Plasma: Liquid portion (about 55% of blood volume); contains water, proteins, electrolytes, nutrients, gases, hormones, and waste products.

• Formed elements: Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

Components of Blood Plasma

Component	Description	Function
Water (91.5%)	Liquid portion of blood	Solvent, suspending medium, absorbs/transports/releases heat
Proteins (7%)	Albumins, globulins, fibrinogen	Maintain osmotic pressure, transport, immunity, clotting
Other solutes (1.5%)	Electrolytes, nutrients, gases, regulatory substances, waste products	Cell function, metabolism, pH regulation, waste removal

Formed Elements of Blood

• Red blood cells (RBCs): Transport oxygen and carbon dioxide; contain hemoglobin.

• White blood cells (WBCs): Defend against infection; several types (neutrophils, lymphocytes, monocytes, eosinophils, basophils).

• Platelets: Cell fragments involved in blood clotting.

Blood Clotting (Hemostasis)

• Vascular spasm: Vasoconstriction to reduce blood loss.

• Platelet plug formation: Platelets adhere to damaged vessel and aggregate.

• Coagulation: Cascade of reactions leading to fibrin clot formation.

Coagulation Pathways:

• Intrinsic pathway: Initiated by damage inside the vessel.

• Extrinsic pathway: Initiated by external trauma.

• Both pathways converge to activate Factor X, leading to the conversion of prothrombin to thrombin and fibrinogen to fibrin.

Blood Types and Transfusion

• ABO blood group: Based on presence of A and/or B antigens on RBCs.

• Rh factor: Presence (+) or absence (−) of D antigen.

• Compatibility is crucial for safe transfusions.

Blood Disorders

• Anemia: Low RBC count or hemoglobin

• Hemophilia: Deficiency of clotting factors

• Leukemia: Cancer of WBCs

• Sickle cell disease: Abnormal hemoglobin

Chapter 20: The Heart

Heart Structure and Function

The heart is a muscular organ that pumps blood through the circulatory system. It consists of four chambers: two atria and two ventricles.

• External features: Anterior cardiac vein, superior/inferior vena cava, pulmonary arteries/veins, aorta, coronary arteries, apex.

• Internal features: Right/left atrium, right/left ventricle, valves (tricuspid, bicuspid/mitral, pulmonary semilunar, aortic semilunar), septa, papillary muscles, chordae tendineae.

Heart Valves

• Atrioventricular (AV) valves: Tricuspid (right), bicuspid/mitral (left)

• Semilunar valves: Pulmonary (right), aortic (left)

Cardiac Cycle and Conduction System

• Cardiac cycle: Sequence of events in one heartbeat, including systole (contraction) and diastole (relaxation).

• Conduction system: Specialized cardiac muscle cells generate and conduct electrical impulses (SA node, AV node, bundle of His, bundle branches, Purkinje fibers).

Key terms: EDV (end-diastolic volume), ESV (end-systolic volume), CO (cardiac output), SV (stroke volume), HR (heart rate)

Cardiac output formula:

$CO = SV \times HR$

Electrocardiogram (ECG/EKG)

• Records electrical activity of the heart.

• Key components: P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

Chapter 21: Blood Vessel Dynamics

Types of Blood Vessels and Structure

Blood vessels transport blood throughout the body. They include arteries, veins, and capillaries, each with distinct structural features.

• Arteries: Carry blood away from the heart; thick, muscular walls.

• Veins: Carry blood toward the heart; thinner walls, often have valves.

• Capillaries: Microscopic vessels for exchange of gases, nutrients, and wastes.

Vessel wall layers: Tunica intima (inner), tunica media (middle), tunica externa (outer)

Blood Vessel Physiology

• Blood pressure: Force exerted by blood on vessel walls.

• Vasoconstriction: Narrowing of blood vessels, increases blood pressure.

• Vasodilation: Widening of blood vessels, decreases blood pressure.

• Capillary exchange: Occurs via diffusion, bulk flow, transcytosis, and filtration.

• Venous return: Assisted by skeletal muscle pump and respiratory pump.

Major Blood Vessels to Know

Arteries	Veins
Brachiocephalic Trunk	R/L Brachiocephalic
Celiac Trunk	R/L Cephalic
External Carotid	R/L External Jugular
Mesenteric arteries	R/L Femoral
R/L Anterior Tibial	R/L Fibular
R/L Axillary	R/L Great Saphenous
R/L Brachial	R/L Internal Iliac
R/L Common Iliac	R/L Internal Jugular
R/L External Iliac	R/L Posterior Tibial
R/L Femoral	R/L Small Saphenous
R/L Fibular	R/L Subclavian
R/L Popliteal	Superior Vena Cava
R/L Posterior Tibial	Inferior Vena Cava
R/L Radial	R/L Common Carotid
R/L Renal	Abdominal Aorta
R/L Subclavian	Ascending Aorta
Thoracic Aorta

Additional info: This table is not exhaustive; refer to course materials for highlighted vessels.

Blood Pressure Regulation

• Mean Arterial Pressure (MAP): Average pressure in arteries during one cardiac cycle.

• MAP is influenced by cardiac output, blood volume, and resistance.

• MAP formula: $MAP = CO \times TPR$ where TPR = total peripheral resistance

Capillary Exchange Mechanisms

• Diffusion: Movement of substances from high to low concentration.

• Bulk flow: Movement of fluid and solutes together due to pressure differences.

• Transcytosis: Transport of large molecules via vesicles.

• Filtration: Movement of fluid out of capillaries; reabsorption: movement of fluid into capillaries.

Venous Return Mechanisms

• Skeletal muscle pump: Muscle contractions help push blood toward the heart.

• Respiratory pump: Changes in thoracic pressure during breathing assist venous return.